Plumber&#39;s heat shield

ABSTRACT

A plumber&#39;s heat shield comprises an arcuate metallic shell attached to a spring-clamp by means of an obedient shaft which enables the heat shield to be moved to any position relative to the spring-clamp. The arcuate shell is preferably formed from aluminum or other material having high infrared reflectivity. The obedient shaft is preferably formed from helically-wound steel spring outer sheath surrounding a ductile copper wire core. The spring steel outer sheath prevents the ductile copper wire core from being bent at too sharp of a radius (which would cause the ductile core to work-harden and fracture) while at the same time protecting the ductile copper wire core from the open-flame of the soldering torch.

CLAIM OF PRIORITY

This is application claims priority of U.S. provisional patentapplication 61/490,044 filed on May 25, 2011.

BACKGROUND OF THE INVENTION

This invention relates generally to hand tools, and in particular tohand tools for use by plumbers.

In the plumbing trade, it is common to sweat together joints in copperpipe and other metal plumbing fittings using an open-flame torchtogether with an appropriate solder or brazing alloy. Often, especiallywhen plumbing repairs are being performed, as opposed to newconstruction, the joint being assembled is in close proximity to wallstuds, insulation, drywall, electrical wiring, or other buildingmaterials that may be damaged by the open-flame torch. Accordingly, itis desirable to have some means of protecting the materials adjacent thejoint being assembled.

Flexible mats formed of a heat resistant fiberglass material arecommonly employed to protect the area around the solder joint, but thesemats are often difficult to place, especially when working overhead asthe mat tends to drop onto the joint itself. The fiberglass mats alsowear out quickly, requiring frequent replacement. Heat resistant gelsare also commonly used to prevent heat damage to protect the areasurrounding the joint during soldering. Heat resistant gels, however,are expensive and cannot be applied to extremely porous surfaces such ascellulose insulation. It is known in the art to form crude heat shieldsfrom soft drink cans, however, these heat shields are difficult toposition properly. Accordingly, what is needed is a reusable, durableheat shield device that can be easily positioned to protect the areasurrounding the joint during soldering regardless of the orientation ofthe joint and the surrounding building materials.

SUMMARY OF THE INVENTION

The present invention comprises a reusable, durable heat shield for usein protecting the area surrounding a solder joint during the solderingprocess. In the illustrative embodiment of the invention, the heatshield comprises an arcuate metallic shell attached to a spring-clamp bymeans of an obedient shaft which enables the heat shield to be moved toany position relative to the spring-clamp. The arcuate shell ispreferably formed from a material having a high infrared reflectivityand low affinity for tin-lead and lead-free soldering alloys. Theobedient shaft is preferably formed from helically-wound steel springouter sheath surrounding a ductile copper wire core. The spring steelouter sheath prevents the ductile copper wire core from being bent attoo sharp of a radius (which would cause the ductile core to work-hardenand fracture) while at the same time protecting the ductile copper wirecore from the open-flame torch.

BRIEF DESCRIPTION OF THE DRAWING

The present invention will be better understood from a reading of thefollowing detailed description, taken in conjunction with theaccompanying drawing figures in which like references designate likeelements and, in which:

FIG. 1 is an exploded, perspective view of a plumber's heat shieldincorporating features of the present invention;

FIG. 2 is a front perspective view of the plumber's heat shield of FIG.1;

FIG. 3 is a rear perspective view of the plumber's heat shield of FIG.1;

FIG. 4 is a perspective view of the plumber's heat shield of FIG. 1 inposition to protect the area surrounding a solder joint during thesoldering operation;

FIG. 5 is a perspective view of an alternative embodiment of an endfitting for attaching the obedient shaft to the heat shield; and

FIG. 6 is a perspective view of another alternative embodiment of an endfitting for attaching the obedient shaft to the heat shield.

DETAILED DESCRIPTION

The drawing figures are intended to illustrate the general manner ofconstruction and are not necessarily to scale. In the detaileddescription and in the drawing figures, specific illustrative examplesare shown and herein described in detail. It should be understood,however, that the drawing figures and detailed description are notintended to limit the invention to the particular form disclosed, butare merely illustrative and intended to teach one of ordinary skill howto make and/or use the invention claimed herein and for setting forththe best mode for carrying out the invention.

With reference to FIGS. 1-3, plumber's heat shield 10 comprises anarcuate shell 12 which is attached to a spring clamp 14 by means ofobedient shaft 16. Arcuate shell 12 preferably comprises a cylindricalsector approximately 4 inches long, having a radius of curvature “R” offrom 1 to 4 inches and preferably about 2 inches and an included angleof between 30 degrees and 180 degrees, preferably about 90 degrees (¼circle).

Arcuate shell 12 is preferably formed of a metallic material having alow affinity for conventional tin-lead solder and lead-free solders,which consist typically of tin, copper, bismuth, and silver. At the sametime arcuate shell 12 has a high reflectivity in the infrared range ofthe electromagnetic spectrum. Steel has low affinity for solder, but haspoor infrared reflectivity. As used herein, a surface has high infraredreflectivity if its reflectivity is better than 70% in the infraredrange of the electromagnetic spectrum. Silver, gold and copper all havegood (high) reflectivity in the infrared range of the electromagneticspectrum (better than 90% if polished to mirror finish), however, allhave high affinity for tin-lead and lead-free solders. Consequently, anysolder that splattered onto the heat shield from the joint beingassembled would be difficult to remove. Silver and gold are also tooexpensive to be of practical use. Aluminum that is polished to a mirrorfinish has the highest reflectance of any metal in the 3,000-10,000 nm(far IR) regions and is significantly less expensive than silver, goldor copper. Aluminum also has significantly lower thermal capacity andtherefore cools faster if accidentally heated. Accordingly, in theillustrative embodiment arcuate shell 12 is made from ⅛ inch thickaluminum with the concave surface 18 being polished to a high gloss (63micro-inches Ra or smoother) or, preferably polished to a mirror finish(8 micro-inches Ra or smoother). Nonmetallic shells, such as thermosetplastics and high temperature thermoplastics, may also be used, providedthe concave surface is coated with a high gloss or mirror finishedaluminum metallization.

Obedient shaft 16 comprises a helically wound steel spring outer sheath20 having an outer diameter of less than about ⅜ of an inch, preferablyabout ¼ inch O.D. Preferably outer sheath 20 is between 12-24 incheslong, preferably about 18 inches long and is wound from conventionalsteel spring wire having a wire diameter of 0.04-0.08 inch in diameterpreferably about 0.026 inch in diameter. The coils of outer sheath 20are preferably close-packed so that outer sheath can bend or elongate,but cannot be compressed. Obedient shaft 16 further comprises a ductilecore 22 (FIG. 6), disposed inside outer sheath 20. Ductile core 22 canbe formed of any malleable material such as steel or aluminum wire butin the illustrative embodiment comprises 12-gauge solid copper wire.Copper has the advantage over steel or aluminum in that it has a lowermodulus of elasticity and therefore is more malleable and, althoughcopper does work harden if bent repeatedly, copper can be annealedsimply by heating. Obedient shaft 16 is capable of supporting a load ofat least 1 ounce cantilevered 18 inches horizontally outward along theobedient shaft without moving.

It is important that obedient shaft 16 be made from a metallic outersheath 20 with a ductile core 22 rather than with conventional goosenecktubing. Although gooseneck tubing is flexible, what the inventor of thepresent invention discovered was that conventional gooseneck tubing,which relies on interference between the helical windings of eachadjacent layer to give the gooseneck tubing its obedience, quickly lostits elastic strength if the flame from the open-flame torch came incontact with the gooseneck tubing. Use of a helically wound steel springouter sheath in combination with a ductile copper wire core enables theobedient shaft of the present invention to resist damage from theopen-flame torch.

Obedient shaft 16 is attached to a shell 12 and spring clamp 14 by meansof fasteners 24 which are assembled through lugs 26 and 28 swaged ontothe ends of obedient shaft 16. In the illustrative embodiment of FIG. 1,fasteners 24 comprise threaded carriage bolts 30 with corresponding nuts32, however, any suitable fastener such as rivets, screws, or adhesivesmay be used without departing from the scope of the invention. Thefasteners 24 are assembled through one of a plurality of apertures 34,36, 38 formed in shell 12, which permit the shell to be positioned indifferent locations depending on the needs of the user. Apertures 34,36, 38 are non-circular (preferably square) to provide an anti-rotationfeature for maintaining the heat shield in a fixed orientation.Alternatively, a lug similar to lug 28 may be utilized at shell 12 toprovide anti-rotation.

Spring-clamp 14 preferably comprises a commercially-available springclamp such as Irwin Tools model 222702 having a jaw opening ofapproximately 2 inches and a handle length of approximately 6 inches.This enables spring-clamp 14 to firmly clamp the edge of standard wallstuds and floor joists (e.g. 2×4's, 2×6's, 2×8's etc.). Obedient shaft16 is attached so that it extends from the handle portion of springclamp 14, although other attachment locations such as the pivot of clamp14 are within the scope of the invention.

As shown in FIG. 4, a solder joint 40, which is made between two piecesof pipe 42 and 44 is frequently in close proximity to a wall stud 46.Therefore, it is desirable to protect wall stud 46 from the flame 48 oftorch 50. This is accomplished using plumber's heat shield 10 byclamping spring-clamp 14 to an adjacent wall stud 52. Arcuate shell 12is then positioned by bending obedient shaft 16 as necessary so that theconcave surface 18 is located behind the solder joint 40 and facingsubstantially toward flame 48. Flame 48 is then applied to heat thejoint to a sufficient temperature for the solder to flow into the joint.Arcuate shell 12 protects wall stud 46 from the heat of flame 48 byreflecting the infrared energy back toward the joint 40. Accordingly,not only does arcuate shell 12 protect wall stud 46, but because theinfrared energy is reflected back toward joint 40, joint 40 is heatedmore quickly than would occur if arcuate shell 12 were not present.

The polished surface 18 of arcuate shell 12 also reflects visible light,so that shield 10 doubles as an inspection mirror to enable the plumberto see the reverse side of the joint being assembled. Thus, not onlydoes the present invention comprise a reusable, durable heat shield, italso saves energy that would otherwise be wasted heating the fiberglassor gel heat absorbing the compounds of the prior art, and it performsthe function of the inspection mirror that the user would otherwise haveto purchase separately.

Although certain illustrative embodiments and methods have beendisclosed herein, it will be apparent from the foregoing disclosure tothose skilled in the art that variations and modifications of suchembodiments and methods may be made without departing from theinvention. For example, although in the illustrative embodiment of FIGS.1-4 obedient shaft 16 is attached by means of blogs 26 and 28, othermethods of attachment such as cable strap 56 (FIG. 5) or pinch bolt 58(FIG. 6) or any other means of attachment are considered within thescope of the invention. Accordingly, it is intended that the inventionshould be limited only to the extent required by the appended claims andthe rules and principles of applicable law. Additionally, as usedherein, references to direction such as “up” or “down” are intend to beexemplary and are not considered as limiting the invention and, unlessotherwise specifically defined, the terms “substantially” or “generally”when used with mathematical concepts or measurements mean within ±10degrees of angle or within 10 percent of the measurement, whichever isgreater.

1. A plumber's heat shield comprising: a clamp having aresiliently-biased jaw; a heat shield member comprising an arcuate shellformed from a material having high infrared reflectivity and lowaffinity for tin-lead and lead-free soldering alloys, the metallicmember having a concave surface, the concave surface having a radius ofcurvature of at least 1 inch; and an obedient shaft, said obedient shaftcomprising an elongate member having a longitudinal axis, a proximal endand a distal end, the proximal end of said obedient shaft including afirst termination rigidly attached to the clamp, the distal end of saidobedient shaft including a second termination removably attached to saidheat shield member.
 2. The plumber's heat shield of claim 1, wherein:the obedient shaft comprises a flexible outer sheath surrounding anelongate ductile core.
 3. The plumber's heat shield of claim 2, wherein:the flexible outer sheath comprises a helically wound steel spring. 4.The plumber's heat shield of claim 2, wherein: the helically wound steelouter sheath comprises a wire helix having a helical radius of less than¼ inch.
 5. The plumber's heat shield of claim 3, wherein: the helicallywound steel outer sheath comprises a wire helix having a wire diameterof 0.04-0.08 inch in diameter.
 6. The plumber's heat shield of claim 2,wherein: the ductile core comprises a copper rod having an outerdiameter less than the inner diameter of the flexible outer sheath. 7.The plumber's heat shield of claim 1, wherein: the resilient jaws of theclamp are capable of clamping a 1¾ inch thick wood edge and supporting aload of at least 1.0 ounce cantilevered 18 inches horizontally outwardalong the obedient shaft.
 8. The plumber's heat shield of claim 1,wherein: the concave surface is a cylindrical surface having an includedangle of between 30 degrees and 180 degrees.
 9. The plumber's heatshield of claim 1, wherein: The radius of curvature of the concavesurface is between 1 inch and 4 inches
 10. The plumber's heat shield ofclaim 1, wherein: the concave surface of the arcuate shell has a surfacefinish of at least 63 micro-inches Ra or smoother.
 11. The plumber'sheat shield of claim 1, wherein the concave surface of the arcuate shellis aluminum.
 12. The plumber's heat shield of claim 11, wherein thearcuate shell is solid aluminum.
 13. The plumber's heat shield of claim1, wherein: the heat shield member comprises a first edge and a secondedge opposite the first edge, the heat shield further including a firstmounting aperture located along the first edge and a second mountingaperture located along the second edge, each of said first and secondmounting apertures capable of receiving the second termination formounting the heat shield to the obedient shaft.
 14. The plumber's heatshield of claim 13, wherein: the aperture includes an anti-rotationfeature for maintaining the second termination in a fixed orientationrelative to said heat shield member.